A car bomb ripped through a market area in a northwest Pakistan tribal town near the Afghan border on Saturday, killing 25 people including three children, officials said.

"The death toll is 25," from the blast in the main bazaar of Landi Kotal in Khyber tribal district, local administration chief Mutahir Zeb told AFP, adding more than 50 people were injured, some of them seriously.

Hospital officials confirmed the toll.

Zeb said there were 18 bodies at the Landi Kotal hospital while seven victims had died while being taken for treatment in Peshawar, the main town in Khyber Pakhtunkhwa province.

The dead included three children aged nine, 10 and 12, he added.

Motor mechanic Sajidullah Khan, who was wounded in the leg, forearms and face, told AFP: "I was checking a car when I heard a huge blast nearby. I knew nothing afterwards and came to in the hospital." Shakoor Jan, an electrician, said he was sitting in his shop when the blast rocked the whole area. "There was fire in several shops," he said.

There was no immediate claim of responsibility but Islamist militants have carried out several attacks in the area.

Since July 2007, a Taliban-led insurgency concentrated in the northwest has fought Pakistan's US-allied government.

Arshad Khan, a local administration official, said the blast appeared to be aimed at members of the pro-government Zakha Khel tribe, who oppose a local warlord, Mangal Bagh. Bagh's Lashkar-i-Islam group has links to Islamist militants and criminal gangs.

"The bomb was planted in a pick-up truck parked near the bus stand," Khan said.

Six shops were gutted and several damaged in the blast, which also destroyed at least eight vehicles, he added.

In the last five years, attacks blamed on Islamist bombers have killed more than 5,000 people in Pakistan according to an AFP tally.

US officials consider the country's semi-autonomous tribal belt a safe haven for Al-Qaeda and insurgents fighting both in Pakistan and across the border in Afghanistan.

Last week a bomb ripped through a passenger bus, killing 19 people, including seven women and a child, on the outskirts of Peshawar.

It was the deadliest attack in months on Peshawar, which has long been a flashpoint for the insurgency.

Pakistan's relations with the United States are in disarray and it has imposed a blockade on NATO supplies crossing overland into Afghanistan since US air strikes killed 24 Pakistani soldiers along the border last November.